Design, flutter and buckling analyses of an adaptive telescope wing configuration

The objective of the presented work is to determine a feasible design concept for a telescope wing and to investigate its aeroelastic properties. As input to an overall performance estimate the added weight and the reduction in available fuel-volume is also estimated. The telescopic outer wing will be used at high altitude to increase operating range and also for start and landing. During high-speed low-level dash the outer wing will be retracted to reduce transonic drag. This work is a part of the Adaptive Structures project at FOI. The wing was made 20% shorter in the spanwise direction and to that the extended telescopic outer wing was added, giving the wing a 20% larger span than for the original wing. The chord of the outer wing is chosen to be 50% of the inner wing chord to fit between the wing beams when retracted. A design concept is presented and fundamental structural strength-calculations have been performed. The aeroelastic model for analyses with the programme MSC/NASTRAN is presented. The configuration denoted Nuk-14-telescope within the project is found to have good flutter-characteristics. The buckling-characteristics of the telescopic wing is determined and compared to that of the original wing. The telescopic wing is estimated to cause a 5% increase in structural-weight of the wing after weight optimisation. The reduction in fuel-capacity is 95 kg per wing if the telescopic outer wing is left empty. A design containing a control-surface in the outer wing has also been analysed. The aeroelastic properties remain satisfying but the structural weight as compared to the original wing is estimated to be 10% higher.